2011-05-23 Jennifer Averett <Jennifer.Averett@OARcorp.com>

	* score/Makefile.am, score/include/rtems/score/thread.h,
	score/inline/rtems/score/thread.inl: Add smp support to dispable
	dispatch level accesses.
	* score/src/threaddispatchdisablelevel.c: New file.

5 files changed, 262 insertions, 49 deletions

diff --git a/cpukit/ChangeLog b/cpukit/ChangeLog
index db98580c86..590165a1f5 100644
--- a/cpukit/ChangeLog
+++ b/cpukit/ChangeLog
@@ -1,3 +1,10 @@
+2011-05-23	Jennifer Averett <Jennifer.Averett@OARcorp.com>
+
+	* score/Makefile.am, score/include/rtems/score/thread.h,
+	score/inline/rtems/score/thread.inl: Add smp support to dispable
+	dispatch level accesses.
+	* score/src/threaddispatchdisablelevel.c: New file.
+
 2011-05-20	Jennifer Averett <Jennifer.Averett@OARcorp.com>
 
 	PR 1787/cpukit
diff --git a/cpukit/score/Makefile.am b/cpukit/score/Makefile.am
index 73d9cee638..9138178e33 100644
--- a/cpukit/score/Makefile.am
+++ b/cpukit/score/Makefile.am
@@ -241,6 +241,10 @@ libscore_a_SOURCES += src/thread.c src/threadchangepriority.c \
     src/threadstackallocate.c src/threadstackfree.c src/threadstart.c \
     src/threadstartmultitasking.c src/threadtickletimeslice.c \
     src/iterateoverthreads.c src/threadblockingoperationcancel.c
+    
+if HAS_SMP
+libscore_a_SOURCES += src/threaddispatchdisablelevel.c
+endif
 
 ## THREADQ_C_FILES
 libscore_a_SOURCES += src/threadq.c src/threadqdequeue.c \
diff --git a/cpukit/score/include/rtems/score/thread.h b/cpukit/score/include/rtems/score/thread.h
index 785d8a149e..c3462024d9 100644
--- a/cpukit/score/include/rtems/score/thread.h
+++ b/cpukit/score/include/rtems/score/thread.h
@@ -464,6 +464,14 @@ SCORE_EXTERN Context_Control _Thread_BSP_context;
  */
 SCORE_EXTERN volatile uint32_t   _Thread_Dispatch_disable_level;
 
+#if defined(RTEMS_SMP)
+  /**
+   * The following declares the smp spinlock to be used to control
+   * the dispatch critical section accesses across cpus.
+   */
+  SCORE_EXTERN SMP_lock_spinlock_nested_Control _Thread_Dispatch_disable_level_lock;
+#endif
+
 /**
  *  The following holds how many user extensions are in the system.  This
  *  is used to determine how many user extension data areas to allocate
@@ -784,6 +792,53 @@ void _Thread_blocking_operation_Cancel(
   ISR_Level                         level
 );
 
+
+#if defined(RTEMS_SMP)
+
+  /** @brief _Thread_Dispatch_initialization
+   * 
+   *  This routine initializes the thread dispatching subsystem.
+   */
+  void _Thread_Dispatch_initialization(void);
+
+  /** @brief _Thread_Dispatch_in_critical_section
+   * 
+   * This routine returns true if thread dispatch indicates
+   * that we are in a critical section.
+   */
+  bool _Thread_Dispatch_in_critical_section(void);
+
+  /** @brief _Thread_Dispatch_get_disable_level
+   * 
+   * This routine returns value of the the thread dispatch level.
+   */
+  uint32_t _Thread_Dispatch_get_disable_level(void);
+
+  /** @brief _Thread_Dispatch_set_disable_level
+   * 
+   * This routine sets thread dispatch level to the 
+   * value passed in.
+   */
+  uint32_t _Thread_Dispatch_set_disable_level(uint32_t value);
+
+  /** @brief _Thread_Dispatch_increment_disable_level
+   *
+   * This rountine increments the thread dispatch level
+   */
+  uint32_t _Thread_Dispatch_increment_disable_level(void);
+
+  /** @brief _Thread_Dispatch_decrement_disable_level
+   * 
+   * This routine decrements the thread dispatch level.
+   */
+  uint32_t _Thread_Dispatch_decrement_disable_level(void);
+
+#else
+  /*
+   * The _Thread_Dispatch_... functions are in thread.inl
+   */
+#endif
+
 #ifndef __RTEMS_APPLICATION__
 #include <rtems/score/thread.inl>
 #endif
diff --git a/cpukit/score/inline/rtems/score/thread.inl b/cpukit/score/inline/rtems/score/thread.inl
index 7ff1e615fb..ba13bda908 100644
--- a/cpukit/score/inline/rtems/score/thread.inl
+++ b/cpukit/score/inline/rtems/score/thread.inl
@@ -31,63 +31,77 @@
  *  @{
  */
 
-/**
- * This routine returns true if thread dispatch indicates
- * that we are in a critical section.
- */
-RTEMS_INLINE_ROUTINE bool _Thread_Dispatch_in_critical_section(void)
-{
-   if (  _Thread_Dispatch_disable_level == 0 )
-    return false;
+#if defined(RTEMS_SMP)
 
-   return true;
-}
+  /*
+   * The _Thread_Dispatch_... functions are prototyped in thread.h.
+   */
 
-/**
- * This routine returns value of the the thread dispatch level.
- */
-RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_get_disable_level(void)
-{
-  return _Thread_Dispatch_disable_level;
-}
+#else
 
-/**
- * This routine sets thread dispatch level to the 
- * value passed in.
- */
-RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_set_disable_level(uint32_t value)
-{
-  _Thread_Dispatch_disable_level = value;
-  return value;
-}
+  /** @brief _Thread_Dispatch_in_critical_section
+   * 
+   * This routine returns true if thread dispatch indicates
+   * that we are in a critical section.
+   */
+  RTEMS_INLINE_ROUTINE bool _Thread_Dispatch_in_critical_section(void)
+  {
+     if (  _Thread_Dispatch_disable_level == 0 )
+      return false;
 
-/**
- * This rountine increments the thread dispatch level
- */
-RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_increment_disable_level(void)
-{
-  _Thread_Dispatch_disable_level++;
-  return _Thread_Dispatch_disable_level;
-}
+     return true;
+  }
 
-/**
- * This routine decrements the thread dispatch level.
- */
-RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_decrement_disable_level(void)
-{
-  _Thread_Dispatch_disable_level--;
-  return _Thread_Dispatch_disable_level;
-}
+  /** @brief _Thread_Dispatch_get_disable_level
+   * 
+   * This routine returns value of the the thread dispatch level.
+   */
+  RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_get_disable_level(void)
+  {
+    return _Thread_Dispatch_disable_level;
+  }
 
-/**
- *  This routine initializes the thread dispatching subsystem.
- */
+  /** @brief _Thread_Dispatch_set_disable_level
+   * 
+   * This routine sets thread dispatch level to the 
+   * value passed in.
+   */
+  RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_set_disable_level(uint32_t value)
+  {
+    _Thread_Dispatch_disable_level = value;
+    return value;
+  }
 
-RTEMS_INLINE_ROUTINE void _Thread_Dispatch_initialization( void )
-{
-  _Thread_Dispatch_set_disable_level( 1 );
-}
+  /** @brief _Thread_Dispatch_increment_disable_level
+   * 
+   * This rountine increments the thread dispatch level
+   */
+  RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_increment_disable_level(void)
+  {
+    _Thread_Dispatch_disable_level++;
+    return _Thread_Dispatch_disable_level;
+  }
+
+  /** @brief _Thread_Dispatch_decrement_disable_level
+   * 
+   * This routine decrements the thread dispatch level.
+   */
+  RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_decrement_disable_level(void)
+  {
+    _Thread_Dispatch_disable_level--;
+    return _Thread_Dispatch_disable_level;
+  }
+
+  /** @brief _Thread_Dispatch_initialization
+   * 
+   *  This routine initializes the thread dispatching subsystem.
+   */
+  RTEMS_INLINE_ROUTINE void _Thread_Dispatch_initialization( void )
+  {
+    _Thread_Dispatch_set_disable_level( 1 );
+  }
 
+#endif
 
 /**
  *  This routine halts multitasking and returns control to
diff --git a/cpukit/score/src/threaddispatchdisablelevel.c b/cpukit/score/src/threaddispatchdisablelevel.c
new file mode 100644
index 0000000000..f0d1cf7a61
--- /dev/null
+++ b/cpukit/score/src/threaddispatchdisablelevel.c
@@ -0,0 +1,133 @@
+/*
+ *  Thread Dispatch Disable Level Methods
+ *
+ *  COPYRIGHT (c) 1989-2011.
+ *  On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#include <rtems/system.h>
+#include <rtems/score/apiext.h>
+#include <rtems/score/context.h>
+#include <rtems/score/interr.h>
+#include <rtems/score/isr.h>
+#include <rtems/score/object.h>
+#include <rtems/score/priority.h>
+#include <rtems/score/states.h>
+#include <rtems/score/sysstate.h>
+#include <rtems/score/thread.h>
+
+void _Thread_Dispatch_initialization( void )
+{
+  _Thread_Dispatch_disable_level = 0; 
+  _SMP_lock_spinlock_nested_Initialize(&_Thread_Dispatch_disable_level_lock);
+  _Thread_Dispatch_set_disable_level( 1 );
+}
+
+bool _Thread_Dispatch_in_critical_section(void)
+{
+  if (  _Thread_Dispatch_disable_level == 0 )
+   return false;
+
+  return true;
+}
+
+uint32_t _Thread_Dispatch_get_disable_level(void)
+{
+  return _Thread_Dispatch_disable_level;
+}
+
+uint32_t _Thread_Dispatch_increment_disable_level(void)
+{
+  ISR_Level  isr_level;
+  uint32_t   level;
+
+  /*
+   * Note: _SMP_lock_spinlock_nested_Obtain returns
+   *       with ISR's disabled and the isr_level that
+   *       should be restored after a short period.
+   *
+   * Here we obtain the lock and increment the 
+   * Thread dispatch disable level while under the
+   * protection of the isr being off.  After this
+   * point it is safe to re-enable ISRs and allow
+   * the dispatch disable lock to provide protection.
+   */
+
+  isr_level = _SMP_lock_spinlock_nested_Obtain(
+    &_Thread_Dispatch_disable_level_lock
+  );
+  
+  _Thread_Dispatch_disable_level++;
+  level = _Thread_Dispatch_disable_level;
+
+  _ISR_Enable(isr_level); 
+
+  return level;
+}
+
+uint32_t _Thread_Dispatch_decrement_disable_level(void)
+{
+  ISR_Level  isr_level;
+  uint32_t   level;
+
+  /*  First we must disable ISRs in order to protect
+   *  accesses to the dispatch disable level.
+   */
+
+  _ISR_Disable( isr_level );
+
+  _Thread_Dispatch_disable_level--;
+  level = _Thread_Dispatch_disable_level;
+
+
+  /* 
+   * Note: _SMP_lock_spinlock_nested_Obtain returns with
+   *        ISR's disabled and _SMP_lock_spinlock_nested_Release
+   *        is responsable for re-enabling interrupts.
+   */
+  _SMP_lock_spinlock_nested_Release( 
+    &_Thread_Dispatch_disable_level_lock,
+    isr_level
+  ); 
+
+  return level;
+}
+
+
+/*
+ * Note this method is taking a heavy handed approach to 
+ * setting the dispatch level. This may be optimized at a 
+ * later timee, but it must be in such a way that the nesting
+ * level is decremented by the same number as the dispatch level.
+ * This approach is safest until we are sure the nested spinlock
+ * is successfully working with smp isr source code.  
+ */
+
+uint32_t _Thread_Dispatch_set_disable_level(uint32_t value)
+{
+  /*
+   * If we need the dispatch level to go higher 
+   * call increment method the desired number of times.
+   */
+
+  while ( value > _Thread_Dispatch_disable_level ) {
+    _Thread_Dispatch_increment_disable_level();
+  }
+
+  /*
+   * If we need the dispatch level to go lower
+   * call increment method the desired number of times.
+   */
+
+  while ( value < _Thread_Dispatch_disable_level ) {
+    _Thread_Dispatch_decrement_disable_level();
+  }
+
+  return value;
+}